<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<link rel="stylesheet" type="text/css" href="/bootstrap/css/bootstrap.css" />
<style type="text/css">
    .container {
        background-color: #dceaf4;
    }
</style>
</head>
<body>
    <div class="container">
        <div class="row">
            <div class="span4">aaa</div>
            <div class="span4">bbb</div>
            <div class="span4">ccc</div>
        </div>
        <div class="row">
            <div class="span2"></div>
            <div class="span8">center</div>
            <div class="span2"></div>
        </div>
        <div class="row">
            <div class="span4">aaa</div>
            <div class="span4 offset4">bbb</div>
        </div>
        <div class="row">
            <div class="span6 offset3">
                <div class="row">
                    <div class="span6">Level 1 column</div>
                </div>
                <div class="row">
                    <div class="span3">Level 2</div>
                    <div class="span3">Level 2</div>
                </div>
                <div class="row">
                    <div class="span3">Level 3</div>
                    <div class="span3">Level 3</div>
                    <div class="span3">Level 3</div>
                </div>
                <div class="row">
                    <div class="span3">Level 4</div>
                    <div class="span3">Level 4</div>
                </div>
            </div>
        </div>
    </div>
    <div class="container">
        <div class="row-fluid">
            <div class="span4">aaa</div>
            <div class="span4">bbb</div>
            <div class="span4">ccc</div>
        </div>
        <div class="row-fluid">
            <div class="span6">aaa</div>
            <div class="span6">bbb</div>
        </div>
        <div class="row-fluid">
            <div class="span12">aaa</div>
        </div>
        <div class="row-fluid">
            <div class="span4 offset4">aaa</div>
            <div class="span4">bbb</div>
        </div>
        <div class="row-fluid">
            <div class="span6 offset3">
                <div class="row-fluid">
                    <div class="span6">Level 1</div>
                </div>
                <div class="row-fluid">
                    <div class="span3">Level 2</div>
                    <div class="span3">Level 2</div>
                </div>
            </div>
        </div>
    </div>
</body>
</html>